THE BRITISH ASSOCIATION AT TORONTO. 45 



States Coast and Geodetic Survey; Prof. Charles D. Walcott (read 

 by Prof. G. K. Gilbert), The Geographical Work of the United 

 States Geological Survey. 



The section of Geology was opened by the address of its presi- 

 dent, Dr. G-. M. Dawson, F. R. S., who gave an admirably clear 

 and unbiased outline of the history and progress of Canadian geol- 

 ogy, with special reference, of course, to the great labors and discov- 

 eries of Logan, Murray, Selwyn, and their co-workers in the Ar- 

 chaean and pre-Cambrian rocks of Canada. Professor Dawson well 

 described and defined the Laurentian and Huronian terranes; but 

 he does not favor the term Algonkian, and does not recognize it as 

 expressing any definite system of rocks between the Huronian and 

 the Cambrian. To go into any discussion of the many interesting 

 papers in this section would be impossible within the limits of this, 

 sketch. A large amount of attention was given to glacial geology, 

 both by American and Canadian contributors — Professors Chamber- 

 lin, Fairchild, Gilbert, Hitchcock, and Willis among the former, 

 and Professors Coleman, Spencer, Taylor, and Tyrrell among the 

 latter. Mr. Tyrrell's account of the succession of the glaciers over 

 Canada was of great interest, indicating three successive centers of 

 ice-sheet movement over the region between the Rocky Mountains 

 and Hudson Bay — the first western, the second central, and the 

 third eastern. In the discussion that followed, some of the British 

 members expressed great interest in this view, as corresponding with 

 indications of a similar shifting of the glacial center of movement 

 in Europe, but in the opposite direction — from the east westward. 

 Prof. John Milne, who gave the evening lecture on Earthquakes 

 and Volcanoes, laid before the section a report — the second made 

 to the association — on Seismological Investigations, in which he de- 

 veloped some striking views. He regards the ocean floors as the 

 great areas of instability and the seat of by far the chief part of 

 seismic movements, and believes it probable that important fault- 

 ings and sinkages are constantly occurring, and that such peculiar 

 abyssal areas as the " Tuscarora deep," etc., and the frequent acci- 

 dents to ocean cables, are evidences of this condition. 



Passing over the sections devoted to biological subjects, zoology, 

 botany, and physiology, in all of which the presidential addresses 

 and the papers and discussions were of abundant interest, a few 

 words must be given to those that dealt with other classes of facts — ■ 

 physical, chemical, and sociological. The address of Professor 

 Ramsay on The Evidences for the Existence of a yet Undiscovered 

 Gas coming between helium and argon in its density and its prop- 

 erties, and describing his elaborately delicate experiments to sepa- 

 rate it, if possible, from helium — though as yet without definite re- 



